Methods of treating subterranean formations using low-molecular-weight fluids

Abstract

The present invention relates to systems and methods useful in subterranean treatment operations. More particularly, the present invention relates to systems and methods for treating subterranean formations using low-molecular weight treatment fluids. Examples of methods of the present invention include methods of fracturing a subterranean formation; methods of enhancing production from multiple subterranean formations penetrated by a well bore during a single trip through the well bore; methods of enhancing production, in real time, from multiple subterranean formations penetrated by a well bore during a single trip through the well bore; and methods of reducing the cost of enhancing production from multiple subterranean formations penetrated by a well bore by stimulating multiple formations, on a single trip through the well bore, with a fluid that minimizes damage to the formation.

1 . A method of fracturing a subterranean formation comprising the steps of: 
 positioning a hydrojetting tool having at least one fluid jet forming nozzle in a portion of the subterranean formation to be fractured;    jetting a low-molecular-weight fluid through the at least one fluid jet forming nozzle against the formation at a pressure sufficient to form a cavity in the formation; and    further jetting the low-molecular-weight fluid through the nozzle to create or enhance at least one fracture in the formation.    
   
   
       2 . The method of  claim 1  wherein the step of further jetting the low-molecular-weight fluid through the nozzle to create or enhance at least one fracture in the formation comprises the step of permitting stagnation pressure in the cavity to create or enhance the at least one fracture.  
   
   
       3 . The method of  claim 1  wherein the pressure sufficient to form a cavity in the formation is a pressure of about two times the pressure required to initiate a fracture in the formation, less the ambient pressure in a well bore adjacent to the formation.  
   
   
       4 . The method of  claim 1  further comprising the step of aligning the at least one fluid jet forming nozzle of the hydrojetting tool with the plane of maximum principal stress in the formation.  
   
   
       5 . The method of  claim 1  wherein the hydrojetting tool comprises a plurality of fluid jet forming nozzles.  
   
   
       6 . The method of  claim 5  wherein the fluid jet forming nozzles are disposed in a single plane.  
   
   
       7 . The method of  claim 5  wherein the fluid jet forming nozzles are disposed in different planes.  
   
   
       8 . The method of  claim 6  further comprising the step of aligning the plane of fluid jet forming nozzles with the plane of maximum principal stress in the formation.  
   
   
       9 . The method of  claim 1  wherein the low-molecular-weight fluid further comprises a proppant.  
   
   
       10 . The method of  claim 9  wherein the proppant is sand.  
   
   
       11 . The method of  claim 9  further comprising the step of slowly reducing the jetting pressure of the low-molecular-weight fluid to thereby allow the at least one created or enhanced fracture to close on the proppant.  
   
   
       12 . The method of  claim 1  wherein the low-molecular-weight fluid has an average molecular weight in the range of from about 100,000 to about 250,000.  
   
   
       13 . The method of  claim 1  wherein the low-molecular-weight fluid has a viscosity of at least about 2 cP, where the viscosity is measured at about 25° C.  
   
   
       14 . The method of  claim 1  wherein the low-molecular-weight fluid comprises an acid system.  
   
   
       15 . The method of  claim 14  wherein the acid system comprises a viscosifier.  
   
   
       16 . The method of  claim 15  wherein the viscosifier comprises an emulsifier or a surfactant.  
   
   
       17 . The method of  claim 14  wherein the acid system comprises a hydrochloric acid based delayed carbonate acid system or a hydrofluoric acid based delayed carbonate acid system.  
   
   
       18 . The method of  claim 1  wherein the low-molecular-weight fluid comprises water.  
   
   
       19 . The method of  claim 1  wherein the low-molecular-weight fluid comprises water, a substantially fully hydrated depolymerized polymer, and a crosslinking agent.  
   
   
       20 . The method of  claim 19  wherein the substantially fully hydrated depolymerized polymer is a depolymerized polysaccharide.  
   
   
       21 . The method of  claim 19  wherein the substantially fully hydrated depolymerized polymer is selected from the group consisting of hydroxypropylguar, carboxymethylhydroxypropylguar, carboxymethylguar, hydroxyethylguar, and carboxymethylhydroxyethylguar.  
   
   
       22 . The method of  claim 19  wherein the substantially fully hydrated depolymerized polymer is present in the low-molecular-weight fluid in an amount in the range of from about 0.2% to about 5% by weight of the water therein.  
   
   
       23 . The method of  claim 19  wherein the low-molecular-weight fluid has a viscosity of at least about 8.5 cP, where the viscosity is measured at 25° C.  
   
   
       24 . The method of  claim 19  wherein the crosslinking agent is a boron-based compound, a compound that comprises zirconium IV ions, a compound that comprises titanium IV ions, an aluminum compound, or a compound that comprises antimony ions.  
   
   
       25 . The method of  claim 19  wherein the crosslinking agent is present in the low-molecular-weight fluid in an amount in the range of from about 50 ppm to about 5000 ppm active crosslinker.  
   
   
       26 . The method of  claim 1  wherein the low-molecular-weight fluid further comprises a pH-adjusting compound, a delayed delinker, a buffer, a surfactant, a clay stabilizer, a fluid loss control agent, a scale inhibitor, a demulsifier, a bactericide, a breaker, an activator, or a mixture thereof.  
   
   
       27 . A method of fracturing a subterranean formation comprising: 
 positioning a hydrojetting tool having at least one fluid jet forming nozzle in a portion of the subterranean formation to be fractured;    jetting a fluid through the at least one fluid jet forming nozzle against the formation at a pressure sufficient to create at least one fracture in the formation; and    pumping a low-molecular-weight fluid into an annulus between the hydrojetting tool and the formation at a rate sufficient to raise the annular pressure to a level sufficient to extend the fracture into the formation.    
   
   
       28 . The method of  claim 27  wherein the fluid that is jetted is a first fluid, and wherein the low-molecular-weight fluid that is pumped into the annulus is a second fluid, and wherein the first fluid is the same fluid as the second fluid.  
   
   
       29 . The method of  claim 28  wherein the second fluid is different than the first fluid.  
   
   
       30 . The method of  claim 27  further comprising the steps of: 
 moving the hydrojetting tool to a different position in the formation;    repositioning the hydrojetting tool in a different portion of the formation;    jetting a fluid through the at least one fluid jet forming nozzle against the formation at a pressure sufficient to create at least one fracture in the formation; and    pumping a low-molecular-weight fluid into the annulus between the hydrojetting tool and the formation at a rate sufficient to raise the annular pressure to a level sufficient to extend the fracture into the formation.    
   
   
       31 . The method of  claim 27  further comprising the step of aligning the fluid jet forming nozzle of the hydrojetting tool with the plane of maximum principal stress in the formation.  
   
   
       32 . The method of  claim 27  wherein the hydrojetting tool comprises a plurality of fluid jet forming nozzles.  
   
   
       33 . The method of  claim 32  wherein the fluid jet forming nozzles are disposed in a single plane.  
   
   
       34 . The method of  claim 32  wherein the fluid jet forming nozzles are disposed in different planes.  
   
   
       35 . The method of  claim 33  further comprising the step of aligning the plane of fluid jet forming nozzles with the plane of maximum principal stress in the formation.  
   
   
       36 . The method of  claim 27  wherein the low-molecular-weight fluid further comprises a proppant.  
   
   
       37 . The method of  claim 36  wherein the proppant is sand.  
   
   
       38 . The method of  claim 27  wherein the low-molecular-weight fluid has an average molecular weight in the range of from about 100,000 to about 250,000.  
   
   
       39 . The method of  claim 27  wherein the low-molecular-weight fluid has a viscosity of at least about 2 cP, where the viscosity is measured at about 25° C.  
   
   
       40 . The method of  claim 27  wherein the low-molecular-weight fluid comprises an acid system.  
   
   
       41 . The method of  claim 40  wherein the acid system comprises a viscosifier.  
   
   
       42 . The method of  claim 40  wherein the acid system comprises a hydrochloric acid based delayed carbonate acid system or a hydrofluoric acid based delayed carbonate acid system.  
   
   
       43 . The method of  claim 27  wherein the low-molecular-weight fluid comprises water.  
   
   
       44 . The method of  claim 27  wherein the low-molecular-weight fluid comprises water, a substantially fully hydrated depolymerized polymer, and a crosslinking agent.  
   
   
       45 . The method of  claim 44  wherein the substantially fully hydrated depolymerized polymer is a depolymerized polysaccharide.  
   
   
       46 . The method of  claim 44  wherein the substantially fully hydrated depolymerized polymer is selected from the group consisting of hydroxypropylguar, carboxymethylhydroxypropylguar, carboxymethylguar, hydroxyethylguar, and carboxymethylhydroxyethylguar.  
   
   
       47 . The method of  claim 44  wherein the substantially fully hydrated depolymerized polymer is present in the low-molecular-weight fluid in an amount in the range of from about 0.2% to about 5% by weight of the water therein.  
   
   
       48 . A method of enhancing production from multiple subterranean formations penetrated by a well bore during a single trip through the well bore, comprising: 
 positioning a hydrojetting tool having at least one fluid jet forming nozzle in a portion of the subterranean formation to be fractured;    jetting a fluid through the at least one fluid jet forming nozzle against the formation at a pressure sufficient to create at least one fracture in the formation;    pumping a low-molecular-weight fluid into an annulus between the hydrojetting tool and the formation at a rate sufficient to raise the annular pressure to a level sufficient to extend the fracture into the formation;    repositioning the hydrojetting tool in a different portion of the formation; and    repeating the steps of jetting a fluid through the at least one fluid jet forming nozzle against the formation at a pressure sufficient to create at least one fracture in the formation and pumping a low-molecular-weight fluid into the annulus between the hydrojetting tool and the formation at a rate sufficient to raise the annular pressure to a level sufficient to extend the fracture into the formation.    
   
   
       49 . The method of  claim 48  wherein the fluid that is jetted is a first fluid, and wherein the low-molecular-weight fluid that is pumped into the annulus is a second fluid, and wherein the first fluid is the same fluid as the second fluid.  
   
   
       50 . The method of  claim 49  wherein the second fluid is different than the first fluid.  
   
   
       51 . The method of  claim 48  wherein the low-molecular-weight fluid further comprises a proppant.  
   
   
       52 . The method of  claim 51  wherein the proppant is sand.  
   
   
       53 . The method of  claim 48  wherein the low-molecular-weight fluid has an average molecular weight in the range of from about 100,000 to about 250,000.  
   
   
       54 . The method of  claim 48  wherein the low-molecular-weight fluid has a viscosity of at least about 2 cP, where the viscosity is measured at about 25° C.  
   
   
       55 . The method of  claim 48  wherein the low-molecular-weight fluid comprises an acid system.  
   
   
       56 . The method of  claim 55  wherein the acid system comprises a viscosifier.  
   
   
       57 . The method of  claim 55  wherein the acid system comprises a hydrochloric acid based delayed carbonate acid system or a hydrofluoric acid based delayed carbonate acid system.  
   
   
       58 . The method of  claim 48  wherein the low-molecular-weight fluid comprises water.  
   
   
       59 . The method of  claim 48  wherein the low-molecular-weight fluid comprises water, a substantially fully hydrated depolymerized polymer, and a crosslinking agent.  
   
   
       60 . The method of  claim 59  wherein the substantially fully hydrated depolymerized polymer is a depolymerized polysaccharide.  
   
   
       61 . The method of  claim 59  wherein the substantially fully hydrated depolymerized polymer is selected from the group consisting of hydroxypropylguar, carboxymethylhydroxypropylguar, carboxymethylguar, hydroxyethylguar, and carboxymethylhydroxyethylguar.  
   
   
       62 . The method of  claim 59  wherein the substantially fully hydrated depolymerized polymer is present in the low-molecular-weight fluid in an amount in the range of from about 0.2% to about 5% by weight of the water therein.  
   
   
       63 . A method of enhancing production, in real time, from multiple subterranean formations penetrated by a well bore during a single trip through the well bore, comprising 
 positioning a hydrojetting tool having at least one fluid jet forming nozzle in a portion of the subterranean formation to be fractured;    jetting a fluid through the at least one fluid jet forming nozzle against the formation at a pressure sufficient to create at least one fracture in the formation;    pumping a low-molecular-weight fluid into an annulus between the hydrojetting tool and the formation at a rate sufficient to raise the annular pressure to a level sufficient to extend the fracture into the formation;    determining, in real time, at least one parameter related to the creation or enhancement of the fracture;    repositioning the hydrojetting tool in a different portion of the formation; and    repeating the steps of jetting a fluid through the at least one fluid jet forming nozzle against the formation at a pressure sufficient to create at least one fracture in the formation and pumping a low-molecular-weight fluid into the annulus between the hydrojetting tool and the formation at a rate sufficient to raise the annular pressure to a level sufficient to extend the fracture into the formation.    
   
   
       64 . The method of  claim 63  wherein the fluid that is jetted is a first fluid, and wherein the low-molecular-weight fluid that is pumped into the annulus is a second fluid, and wherein the first fluid is the same fluid as the second fluid.  
   
   
       65 . The method of  claim 64  wherein the second fluid is different than the first fluid.  
   
   
       66 . The method of  claim 63  wherein the step of determining, in real time, at least one parameter related to the creation or enhancement of the fracture comprises determining, in real time, that at least one fracture therein has been created or enhanced to a desired extent.  
   
   
       67 . The method of  claim 63  wherein the step of relocating the hydrojetting tool within the well bore to another desired location in the same, or different, formation is performed after the step of determining, in real time, that at least one fracture therein has been created or enhanced to a desired extent.  
   
   
       68 . The method of  claim 63  further comprising performing a remediative step after the step of determining, in real time, at least one parameter related to the creation or enhancement of the fracture.  
   
   
       69 . The method of  claim 68  wherein the remediative step comprises reducing the concentration of a proppant present in the low-molecular-weight fluid.  
   
   
       70 . The method of  claim 68  wherein the remediative step comprises reducing the viscosity of the low-molecular-weight fluid.  
   
   
       71 . The method of  claim 63  wherein the low-molecular-weight fluid further comprises a proppant.  
   
   
       72 . The method of  claim 71  wherein the proppant is sand.  
   
   
       73 . The method of  claim 63  wherein the low-molecular-weight fluid has an average molecular weight in the range of from about 100,000 to about 250,000.  
   
   
       74 . The method of  claim 63  wherein the low-molecular-weight fluid has a viscosity of at least about 2 cP, where the viscosity is measured at about 25° C.  
   
   
       75 . The method of  claim 63  wherein the low-molecular-weight fluid comprises an acid system.  
   
   
       76 . The method of  claim 75  wherein the acid system comprises a viscosifier.  
   
   
       77 . The method of  claim 75  wherein the acid system comprises a hydrochloric acid based delayed carbonate acid system or a hydrofluoric acid based delayed carbonate acid system.  
   
   
       78 . The method of  claim 63  wherein the low-molecular-weight fluid comprises water.  
   
   
       79 . The method of  claim 63  wherein the low-molecular-weight fluid comprises water, a substantially fully hydrated depolymerized polymer, and a crosslinking agent.  
   
   
       80 . The method of  claim 79  wherein the substantially fully hydrated depolymerized polymer is a depolymerized polysaccharide.  
   
   
       81 . The method of  claim 79  wherein the substantially fully hydrated depolymerized polymer is selected from the group consisting of hydroxypropylguar, carboxymethylhydroxypropylguar, carboxymethylguar, hydroxyethylguar, and carboxymethylhydroxyethylguar.  
   
   
       82 . The method of  claim 79  wherein the substantially fully hydrated depolymerized polymer is present in the low-molecular-weight fluid in an amount in the range of from about 0.2% to about 5% by weight of the water therein.  
   
   
       83 . A method of reducing the cost of enhancing production from multiple subterranean formations penetrated by a well bore by stimulating multiple formations, on a single trip through the well bore, with a fluid that minimizes damage to the formation comprising: 
 positioning a hydrojetting tool having at least one fluid jet forming nozzle in a portion of the subterranean formation to be fractured;    jetting a fluid through the at least one fluid jet forming nozzle against the formation at a pressure sufficient to create at least one fracture in the formation;    pumping a low-molecular-weight fluid into an annulus between the hydrojetting tool and the formation at a rate sufficient to raise the annular pressure to a level sufficient to extend the fracture into the formation;    repositioning the hydrojetting tool in a different portion of the formation; and repeating the steps of jetting a fluid through the at least one fluid jet forming nozzle against the formation at a pressure sufficient to create at least one fracture in the formation and pumping a low-molecular-weight fluid into the annulus between the hydrojetting tool and the formation at a rate sufficient to raise the annular pressure to a level sufficient to extend the fracture into the formation;    wherein the low-molecular-weight fluid enhances the regain permeability of the subterranean formation.    
   
   
       84 . The method of  claim 83  wherein the fluid that is jetted is a first fluid, and wherein the low-molecular-weight fluid that is pumped into the annulus is a second fluid, and wherein the first fluid is the same fluid as the second fluid.  
   
   
       85 . The method of  claim 84  wherein the second fluid is different than the first fluid.  
   
   
       86 . The method of  claim 83  wherein the low-molecular-weight fluid further comprises a proppant.  
   
   
       87 . The method of  claim 86  wherein the proppant is sand.  
   
   
       88 . The method of  claim 83  wherein the low-molecular-weight fluid has an average molecular weight in the range of from about 100,000 to about 250,000.  
   
   
       89 . The method of  claim 83  wherein the low-molecular-weight fluid has a viscosity of at least about 2 cP, where the viscosity is measured at about 25° C.  
   
   
       90 . The method of  claim 83  wherein the low-molecular-weight fluid comprises an acid system.  
   
   
       91 . The method of  claim 90  wherein the acid system comprises a viscosifier.  
   
   
       92 . The method of  claim 90  wherein the acid system comprises a hydrochloric acid based delayed carbonate acid system or a hydrofluoric acid based delayed carbonate acid system.  
   
   
       93 . The method of  claim 83  wherein the low-molecular-weight fluid comprises water.  
   
   
       94 . The method of  claim 83  wherein the low-molecular-weight fluid comprises water, a substantially fully hydrated depolymerized polymer, and a crosslinking agent.  
   
   
       95 . The method of  claim 94  wherein the substantially fully hydrated depolymerized polymer is a depolymerized polysaccharide.  
   
   
       96 . The method of  claim 94  wherein the substantially fully hydrated depolymerized polymer is selected from the group consisting of hydroxypropylguar, carboxymethylhydroxypropylguar, carboxymethylguar, hydroxyethylguar, and carboxymethylhydroxyethylguar.  
   
   
       97 . The method of  claim 94  wherein the substantially fully hydrated depolymerized polymer is present in the low-molecular-weight fluid in an amount in the range of from about 0.2% to about 5% by weight of the water therein.